ANIMAL BEHAVIOUR (ABG 503) LECTURE NOTES Aims of the course 1. To understand the general concepts that govern the manner in which animals behave throughout their lives i.e. maximizing 'fitness' through essentially selfish actions. 2. To appreciate the range of mechanisms by which animals adapt to their environmental conditions using behavioural actions. 3. To achieve competence in the skills required to conduct scientifically meaningful studies of animal behaviour. Brief history of the study of animal behaviour 1. First ethologists (pre-historic humans) studied behavior for practical purposes: i. Prey behaviour was studied for hunting. ii. Domestication - dogs, cats, ox, cattle, reindeer, horses, etc. 2. Natural theologians during the Middle Ages documented behaviour as part of general biology of organisms. 3. From early 1900s - animal behaviour became a formal discipline. 4. From late 1900s and early 2000 - modern studies of animal behaviour. Introduction Behaviour can be defined as an expressed course of action produced in organisms in response to stimulus from a given situation. It could simply be considered as what the animal does. The fundamental explanation of behavioural activity must begin with a stimulus and end with a response. Stimulus: Any change in the biotic and abiotic environments capable of eliciting or causing some sort of reaction or response in a living organism. For example, temperature, pressure, radiation, gravity, or activities of other organisms within the immediate environment. Approaches to behavioural studies i. Vitalistic approach Behavioural activities are explained in terms of what animals are seen to do in relation to changes in the environment. It involves total rejection of any study of the animal outside its natural environment. The technique is non-scientific since all the observations relate to past events which cannot be tested experimentally. ii. Mechanistic approach It is an experimental approach and involves the study of particular aspects of behaviour under controlled conditions in a laboratory. It was pioneered by Pavlov and used extensively in psychological study. It may be criticized on the basis of the artificiality of the experimental conditions and the way in which results are interpreted. iii. Ethological approach Ethology is the scientific study of animal behaviour. It explains responses observed in the field in terms of stimuli eliciting the behaviour. This was pioneered by Lorenz, von Frisch and Tinbergen. Ethologists have so far tried to answer questions about animal behaviour from four major areas: 1. The evolutionary history: - How did various forms of behaviour evolved? i.e. (Innate/instinctive/genetic or learned?) - How does the behaviour compare with similar behaviour in related species? 1 2. Development: - How does behaviour change with age? - What are the early experiences necessary for the behaviour to expressed? - e.g. How does courtship behaviour develop during the individuals’s life? - Does the male in domestic fowl learn the waltz dance? - Does he practice dancing? - Is he successful in directing the female? 3. Causation: What are the stimuli that elicit the response? How has it been modified by recent learning? 4. Function: How does the behaviour impact on the animal’s chances of survival and reproduction? I. Components (types) of Behaviour Nature/innate Nurture/learned Instinct or genes Experience and learning determine behaviour influence behaviour 1. Learned behaviour Learning can be defined as an adaptive change in individual behaviour as a result of experience. The degree of permanence of newly acquired learned behaviour patterns depends on memory storing information gained from the experience. Learning alters the range of behaviours shown by an individual, and allows it to adapt to and control its environment. Types of learned behaviours i. Habituation Ideally, an animal should recognize important cues or signals in its environment and act in response to them in order to adapt to constantly changing environment. *Continuous repetition of a stimulus not associated with reward or punishment (reinforcement) puts off any response to the stimulus. E.g. birds learn to ignore scare crow. Particularly important is the reaction to new signals. The importance of these signals have to be assessed, and the animal has to work out how to react to them. This is where learning is important - a suitable response can be learnt, rather than a trial and error effort after each presentation of the same stimulus. Take for example a rat that has just experienced an aversive stimulus (e.g. a very bright light). Immediately after this event, the rat may be extra sensitive to other cues (such as noises or lights) that it would not normally respond to. This is sensitization, a period of increased responsiveness following a reward or punishment (or 'reinforcement'). However, if the second stimulus is repeated without the reinforcer, the response of the animal should become reduced, and the stimulus may even be completely ignored eventually. This is habituation. The animal learns not to respond to irrelevant stimuli. This decline in response is specific to a given stimulus. If a new stimulus is presented the animal will react (i.e. it has not ceased responding simply 2 because it is tired). Animals will not habituate to relevant stimuli e.g. those associated with predators, food or mates. Habituation is important in the development of a behaviour in young animals and helping to understand neutral elements in the environment, such as movements due to wind, cloud, shadows, wave action etc. It is based in the nervous system and is not a form of sensory adaptation since the behaviour is permanent and no response is ever shown to the stimulus after the period of habituation. ii. Associative learning Associative learning simply means that an animal learns to associate an event with a result. There are two types of associative learning: classical (Pavlovian) conditioning, and instrumental (operant or trial-and-error) conditioning. a. Classical (Pavlovian) conditioning (conditioned reflex): Pavlovian conditioning involves the association of events over which the animal has no control. It is able to gain prediction of events in its environment. Pavlov's dog associated bell with the arrival of food and begins to salivate at the sound of a bell. At first, the dog didn't react to the stimulus alone, but after a few repetitions the stimulus was able to cause salivation, before the arrival of the food being given to the dog. The animal learns to associate a conditioned stimulus (e.g. a bell), with the onset of an unconditioned stimulus (e.g. the arrival of food). An unconditioned response (e.g. salivation) would only occur in response to an unconditioned stimulus prior to learning. Birds avoid eating black and orange cinnabar moth larvae because of bad taste and avoid all similarly coloured larvae even though they may be nutritious. b. Operant conditioning (trial-and-error learning): Trial-and-error activities give rise to responses which are reinforced either by rewarding (positive) or punishment (negative). The association of outcome of a response in terms of reward or punishment increases or decreases respectively future responses. Instrumental conditioning therefore involves association of events with control. Possibly the most famous set of experiments examining this sort of learning were done by followers of the school of B.F. Skinner. The classic tool is the Skinner box. Here, the animal is placed in the box, which has some sort of reward for conducting a behaviour. For example, if the animal presses a lever, it receives a food pellet. By trial and error, the animal learns that pressing the lever delivers the reward. In this way, the animal gains prediction and control over events in its environment. The animal learns to associate its own behaviour with a particular outcome. If the outcome is rewarding e.g. access to food, the animal learns to repeat the behaviour that resulted in food access previously. It therefore learns a conditioned response to obtain food (unconditioned response). iii. Latent or exploratory learning Animals explore new surroundings and learn information which may be useful at a later stage (hence latent) and mean the difference between life and death. E.g. In mice, knowledge of the immediate environment of its burrow may help it escape from a predator. At the time of acquiring this knowledge, it ha no apparent value, hence not all behavioural activities are apparently directed to satisfying a need or obtaining a reward. iv. Insight learning This is the highest form of learning which does not result from immediate trial-and-error learning but may be based on information previously learned by other behavioural activities. Insight learning is based on advanced perceptual abilities such as thought and 3 reasoning. Kohlar’s work on chimpanzees suggested insight learning: when presented with wooded boxes and bananas too high to reach, the chimps stacked up the boxes beneath the bananas and climbed up to get them. This response appeared to follow a period of ‘apparent thought’. Previous experience of playing with boxed (latent learning) may have increased the likelihood of the response. v. Imprinting A simple and specialized form learning occurring during receptive periods in an animal’s life. Imprinting involves young animals becoming associated with, and identifying themselves with another organism, usually a parent, or some large object. E.g. Chicks hatch with an innate tendency to approach and follow their mother. They have already imprinted on her vocalizations. After hatching (24 - 36 hours) they imprint on her visual appearance. Geese and ducklings form social attachments shortly after birth. Lorenz found that goslings deprived of their parents would follow him and use him as a substitute parent. Pet lambs or kids bottle fed show similar behaviour. This may have a profound and undesirable effect later in life when the animal finds it difficult in forming normal relationships with others of the same species as exemplified by sexual imprinting (direct sexual behaviour of members of the same species).